Generally, in a motor, a rotor is rotated by electromagnetic interaction between the rotor and a stator. In this case, a rotational shaft inserted into the rotor is also rotated to generate a rotational driving force.
Here, the rotor may be classified into a surface permanent magnet (SPM) type rotor and an interior permanent magnet (IPM) type rotor according to a coupling structure of a magnet provided at a rotor core.
Here, the interior permanent magnet type rotor has a configuration in which a pocket is provided in the rotor core and the magnet is inserted into the pocket. On the other hand, the surface permanent magnet type rotor has a configuration in which the magnet is attached to an outer circumferential surface of the rotor core.
Meanwhile, in the surface permanent magnet type rotor, a guide protrusion may be formed on the outer circumferential surface of the rotor core in order to align a position of the magnet and to enhance a coupling ability between the rotor core and the magnet. The guide protrusion is elongated in an axial direction of the rotor to form a slot into which the magnet is inserted from the outer circumferential surface of the rotor core.
However, the above-described configuration of the rotor core has a problem in that a design is complicated and manufacturing cost is increased. This is because the number of guide protrusions is varied according to the number of poles of the motor, and thus a shape of the rotor core is changed. That is, there is a problem in that the rotor cores corresponding to the number of poles of the motor should be separately manufactured.